<!DOCTYPE html>
<html>
<head>
    <title>Bootstrap 实例</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css">
    <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script>
    <script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script>
    <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container-fluid">
    <h1>Hello World!</h1>
    <p>重置浏览器大小查效果。</p>
    <p> 在移动设备上，即屏幕宽度小于 576px 时，四个列将会上下堆叠排版。</p>
    <div class="row">
        <div class="col-sm-3" style="background-color:lavender;">.col-sm-3</div>
        <div class="col-sm-3" style="background-color:lavenderblush;">.col-sm-3</div>
        <div class="col-sm-3" style="background-color:lavender;">.col-sm-3</div>
        <div class="col-sm-3" style="background-color:lavenderblush;">.col-sm-3</div>
    </div>
</div>


</body>
</html>